Americans have worried about the performance of our public schools for decades, and the charter school movement arose during the 1990s when some education reformers decided that government regulations kept traditional public schools from changing their policies and curriculums, streamlining their budgets, and holding themselves accountable for student performance. While traditional public schools operate under the control of local school boards, charter schools receive renewable contracts from cities, states, and nonprofits and usually stay open if their students meet state standards and pass national standardized tests at acceptable rates. Since the first charter schools opened thirty years ago, their visibility and popularity have increased dramatically; between 2000-2001 and 2015-2016, the number of students who attend charter schools nationwide has increased from 400,000 students to 2.9 million, and this population has grown about 10-15% every year since the mid-2000s. While advocates of charter schools claim that these programs save money and improve student outcomes compared with traditional public schools, the opponents of the charter movement question the academic benefits of charter schools and underscore how much stress charters place upon local school districts. Charter schools still only work with about 5-6% of all American students, but Secretary of Education Betsy DeVos clearly believes charter schools and voucher programs represent the future of American education. We must accordingly examine how well charter schools perform compared with public schools and whether their potential drawbacks make them a distraction from more-useful education reforms.

The Center for Research on Education Outcomes (CREDO) at Stanford University released its second comprehensive study comparing charter schools and traditional public schools with similar demographics in 2013, and the study produced three main results: 1) Charter schools have improved significantly since the first CREDO study from 2009. 2) Traditional public schools and charter schools provide nearly the same amount of academic growth for their students. 3) Charter schools have the most success with poor African-Americans and Hispanic-Americans, English-Language Learners, and students from all backgrounds who need special education services. When CREDO published its 2009 study, traditional public schools outperformed charter schools for Math and Reading across every social, economic, and racial category. The students who attended charter schools received the equivalent of seven fewer days of Reading instruction and twenty-two fewer days of Math instruction than their traditional public school counterparts. The 2013 study, however, concluded that students from charter schools had eight more days of Reading growth than students from traditional public schools and the same average Math performance. Overall, charters and traditional public schools currently provide about the same quality of education for their students, but charter schools have disproportionate benefits for demographics that public schools often leave behind (see chart below).

When we compare charter schools and traditional public schools from the same regions, we similarly find that 56% of charter schools have the same performance as traditional public schools for Reading while 25% perform noticeably better and another 19% perform significantly worse. Charter schools and traditional public schools are equally successful for Math, where 40% have the same performance, 29% perform significantly better than public schools and 31% perform significantly worse. Unfortunately, the similar achievement of charter schools and traditional public schools provides useful evidence for proponents and detractors of charter schools alike. Supporters of the charter movement rightfully assert that charter schools have already reached the academic performance of traditional public schools and firmly believe these schools will continue improving over time. Detractors, conversely, ask why education reformers have spent so much effort and money on charter schools that have not meaningfully improved American education. In fact, recent studies which have compared traditional public schools with charter schools without removing better-funded (and predominantly white) suburban schools from their data-sets have found that traditional public schools still slightly outperform charter schools nationwide.

So the question remains: do charter schools improve education? If not, will they improve our school systems eventually if they receive more time and resources? While I personally believe policymakers should wait another few years and then make their final assessments based upon the next set of CREDO results, we should remember that charter schools have direct competitive advantages over traditional public schools and multiple drawbacks beyond the central problem of student achievement. First, charter schools have smaller class sizes and student populations than traditional public schools, and these secondary variables positively affect student performance (see table below). Second, charter schools do not admit students after the start of the school-year and can require outside support from the parents of their students. Finally, charter schools have fewer curriculum restrictions than other public schools, which provides their instructors with more opportunities for innovation. Charter schools may have improved significantly over time, but these advantages mean that some of their success may not arise from the categorical effectiveness of charter schools themselves.

Figure 3. Percentage of Classrooms with Different Sizes for Charter Schools and Traditional Public Schools (Source: Chudowsky and Ginsburg)

Recent reports have also raised the problem of how traditional school districts can teach their own students while their revenues decline from reduced enrollment. While public schools have started the transition towards leaner budgets, the fixed costs associated with pensions for retired teachers, school facilities, and higher instructor salaries mean they cannot make the necessary cuts without further reducing their budgets for academic and extracurricular programs. This pushes even more students out of traditional schools and into the charter system, which gradually weakens the entire school district. Some states have eased this burden with reimbursement programs where local charter schools help fund district pensions and with temporary subsidies that help traditional public schools downsize, but most of these policies have received limited financial and political support. Most Americans still attend traditional public schools, and the vicious cycle of reduced enrollment, less money for student programs, and mass relocation into charter schools could have significant consequences within the next ten-fifteen years. Furthermore, if the government continues to support charter schools at the expense of public schools, then students from rural areas may not have access to schools near their hometowns. Perhaps the only one-sided conclusion I have drawn from current research into charter schools is the wholesale failure of digital charter schools: CREDO published another report last year showing that students from online charter schools receive the equivalent of 72 fewer days of Math instruction and 180 fewer days of Reading instruction than students from other public schools using the standard 180-day school-year. Despite the support of Secretary DeVos for online charters, these schools clearly do not benefit their students and should become immediate targets for reform or closure.

Whether or not charter schools should become significant parts of the future of American education depends on whether they can demonstrate continued improvement beyond the performance of traditional public schools, how well this policy solution will scale once the charter system serves higher numbers of students, and the short-term and long-term effects of charter schools on district budgets. The path forward should likely involve the following: 1) State governments should close the bottom 10% of all charter schools, which could increase the achievement of charter students for Math and Reading the equivalent of about fifteen days of learning. 2) Researchers should confirm the consensus among education researchers that students from charter schools and traditional public schools currently show similar academic growth and reevaluate these results within the next few years. If charters cannot surpass other public schools collectively, then the state and federal governments should devote their time and resources towards other education reforms including flipped classrooms, project-based learning, and student-directed study (my previous post about Salman Khan discusses these options). 3) State and local governments should help schools districts make the budget cuts associated with reduced enrollment so that they will not need to divert resources away from current students. Charter schools will not solve all of the problems with American education, but recent evidence shows they can help our students if we think critically about their costs and benefits.